Piston assembly 02/203221 Perkins RG +0.50 mm, genuine

For the Perkins 1104 (RG) engine: piston assembly 02/203221, +0.50 mm, a genuine JCB part. The card also lists 4115P016, T426389, 10000-95331. The photo shows the Perkins marking on the piston skirt.

The piston size follows the bore: a standard piston for an unmachined bore, an oversize piston after the bore has been machined and honed. The combustion bowl in the crown and the ring grooves differ between engine versions, so the piston is selected by engine code and part number. Scoring, a burnt crown or a broken ring land call for a new piston. This is a direct-injection engine: fuel is injected into the bowl in the piston crown and combustion starts there. Pistons in one engine should be close in weight, so when a single piston is replaced the weight difference is checked too. The piston pin and rings are checked together with the piston.

Specifications

Compatibility

The part is listed for JCB machines fitted with these engines. An oversize piston is used together with rings of the same size; the bores are machined to suit it. The catalogue also has the aftermarket version of this part. Other parts are in Perkins engine.

Fitting

When fitting the gudgeon pin the piston can be warmed slightly in warm oil; the pin must go in without force. Seat the circlips fully in their grooves. During the first hours after assembly, watch the oil level and exhaust smoke. After assembly, compression can be measured to compare the cylinders. Fit the pistons to the rods by their direction mark.